From: Heiko Carstens <hca@xxxxxxxxxxxxx> commit 1389f17937a03fe4ec71b094e1aa6530a901963e upstream. arch_ftrace_get_regs is supposed to return a struct pt_regs pointer only if the pt_regs structure contains all register contents, which means it must have been populated when created via ftrace_regs_caller. If it was populated via ftrace_caller the contents are not complete (the psw mask part is missing), and therefore a NULL pointer needs be returned. The current code incorrectly always returns a struct pt_regs pointer. Fix this by adding another pt_regs flag which indicates if the contents are complete, and fix arch_ftrace_get_regs accordingly. Fixes: 894979689d3a ("s390/ftrace: provide separate ftrace_caller/ftrace_regs_caller implementations") Reported-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Reported-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx> Reviewed-by: Sven Schnelle <svens@xxxxxxxxxxxxx> Acked-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx> Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/s390/include/asm/ftrace.h | 10 ++++++---- arch/s390/include/asm/ptrace.h | 2 ++ arch/s390/kernel/ftrace.c | 2 +- arch/s390/kernel/mcount.S | 9 +++++++++ 4 files changed, 18 insertions(+), 5 deletions(-) --- a/arch/s390/include/asm/ftrace.h +++ b/arch/s390/include/asm/ftrace.h @@ -47,15 +47,17 @@ struct ftrace_regs { static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs) { - return &fregs->regs; + struct pt_regs *regs = &fregs->regs; + + if (test_pt_regs_flag(regs, PIF_FTRACE_FULL_REGS)) + return regs; + return NULL; } static __always_inline void ftrace_instruction_pointer_set(struct ftrace_regs *fregs, unsigned long ip) { - struct pt_regs *regs = arch_ftrace_get_regs(fregs); - - regs->psw.addr = ip; + fregs->regs.psw.addr = ip; } /* --- a/arch/s390/include/asm/ptrace.h +++ b/arch/s390/include/asm/ptrace.h @@ -15,11 +15,13 @@ #define PIF_EXECVE_PGSTE_RESTART 1 /* restart execve for PGSTE binaries */ #define PIF_SYSCALL_RET_SET 2 /* return value was set via ptrace */ #define PIF_GUEST_FAULT 3 /* indicates program check in sie64a */ +#define PIF_FTRACE_FULL_REGS 4 /* all register contents valid (ftrace) */ #define _PIF_SYSCALL BIT(PIF_SYSCALL) #define _PIF_EXECVE_PGSTE_RESTART BIT(PIF_EXECVE_PGSTE_RESTART) #define _PIF_SYSCALL_RET_SET BIT(PIF_SYSCALL_RET_SET) #define _PIF_GUEST_FAULT BIT(PIF_GUEST_FAULT) +#define _PIF_FTRACE_FULL_REGS BIT(PIF_FTRACE_FULL_REGS) #ifndef __ASSEMBLY__ --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -291,7 +291,7 @@ void kprobe_ftrace_handler(unsigned long regs = ftrace_get_regs(fregs); p = get_kprobe((kprobe_opcode_t *)ip); - if (unlikely(!p) || kprobe_disabled(p)) + if (!regs || unlikely(!p) || kprobe_disabled(p)) goto out; if (kprobe_running()) { --- a/arch/s390/kernel/mcount.S +++ b/arch/s390/kernel/mcount.S @@ -27,6 +27,7 @@ ENDPROC(ftrace_stub) #define STACK_PTREGS_GPRS (STACK_PTREGS + __PT_GPRS) #define STACK_PTREGS_PSW (STACK_PTREGS + __PT_PSW) #define STACK_PTREGS_ORIG_GPR2 (STACK_PTREGS + __PT_ORIG_GPR2) +#define STACK_PTREGS_FLAGS (STACK_PTREGS + __PT_FLAGS) #ifdef __PACK_STACK /* allocate just enough for r14, r15 and backchain */ #define TRACED_FUNC_FRAME_SIZE 24 @@ -57,6 +58,14 @@ ENDPROC(ftrace_stub) .if \allregs == 1 stg %r14,(STACK_PTREGS_PSW)(%r15) stosm (STACK_PTREGS_PSW)(%r15),0 +#ifdef CONFIG_HAVE_MARCH_Z10_FEATURES + mvghi STACK_PTREGS_FLAGS(%r15),_PIF_FTRACE_FULL_REGS +#else + lghi %r14,_PIF_FTRACE_FULL_REGS + stg %r14,STACK_PTREGS_FLAGS(%r15) +#endif + .else + xc STACK_PTREGS_FLAGS(8,%r15),STACK_PTREGS_FLAGS(%r15) .endif lg %r14,(__SF_GPRS+8*8)(%r1) # restore original return address Patches currently in stable-queue which might be from hca@xxxxxxxxxxxxx are queue-5.16/s390-extable-fix-exception-table-sorting.patch queue-5.16/s390-ftrace-fix-arch_ftrace_get_regs-implementation.patch queue-5.16/s390-ftrace-fix-ftrace_caller-ftrace_regs_caller-generation.patch